Abstract African Americans (AAs) have a greater risk for poor cognitive aging compared to White Americans, whether measured as clinical dementia or as lower cognitive function in late life. Previous research indicates that while older AAs demonstrate poorer cognitive function, they do not have faster declines after age 65 compared to their White counterparts, indicating that perhaps differences emerge earlier than 65. However, few studies have assessed cognition in both middle and late life in AA populations. Further, we have a limited understanding of the processes that drive risk for poor cognitive outcomes or the moderators that may act as resilience factors in these populations. AAs living in disadvantaged neighborhoods experience a disproportionate burden of socioeconomic stressors throughout life at both the individual (e.g., economic disadvantage) and the neighborhood (e.g., lack of access to services, disorder) level. AAs also experience substantial disparities in diet and weight compared to Whites. Both of these factors are known influences on cognitive function and are themselves influenced by neighborhood and individual stress, potentially explaining these associations. In response to NOT-AG-18-008, this administrative supplement proposes to add measures of cognitive function and clinically adjudicated Mild Cognitive Impairment and Alzheimer's Disease to our ongoing NCI-funded study (CA149105) that is following a cohort of mid- to late- life African Americans residing in two low-income neighborhoods. The proposed supplement will build on the parent study's rich existing data, which includes repeated measures of individual- and neighborhood-level socioeconomic conditions from 2011 through 2018. While the focus of the currently funded (parent) study is on neighborhood socioeconomic conditions, dietary intake and BMI, we will use the supplement to address new aims examining the role of diet, the neighborhood environment and BMI in explaining the association of individual- and neighborhood-level characteristics to cognitive function and clinically-adjudicated cognitive outcomes. This additional data collection will provide us with preliminary data to support a planned R01 submission focused on individual and neighborhood-level socioeconomic conditions and cognitive decline/ Alzheimer's disease risk in this high-risk cohort. Aims include: 1) Characterize cognitive function and the prevalence of Mild Cognitive Impairment and Dementia in a sample of disadvantaged AAs aged 50 years and older; 2) Evaluate the relationship between individual and neighborhood socio-economic conditions and cognitive function and clinical cognitive outcomes; 3) Examine the direct, potentially reciprocal relationship between diet (e.g., omega-3 polyunsaturated fatty acids, alcohol, and B vitamins), BMI and cognitive outcomes. Further, explore diet and BMI as mechanisms that explain any relationships between socio-economic conditions and cognitive outcomes and impairment.